So it’s official, Yahoo is indeed buying Tumblr for a huge wad of cash, but as you can see from this animated GIF being shared on the social blogging platform, many Tumblr members aren’t quite buying Yahoo CEO Marissa Mayer’s promise “not to screw it up.”

Tumblr members may be afraid Yahoo will change it, suck it dry and neglect it. But Mayer’s post announcing the deal does indicate she does get what Tumblr’s about, starting with the animated GIF at the top of the post:

She went on to say:

“We promise not to screw it up. Tumblr is incredibly special and has a great thing going. We will operate Tumblr independently. David Karp will remain CEO. The product roadmap, their team, their wit and irreverence will all remain the same as will their mission to empower creators to make their best work and get it in front of the audience they deserve. Yahoo! will help Tumblr get even better, faster.”

In his own Tumblr post, the understandably elated Karp, who now joins the ranks of young and insanely rich Internet entrepreneurs, described why Tumblr members have nothing to worry about:

“Before touching on how awesome this is, let me try to allay any concerns: We’re not turning purple. Our headquarters isn’t moving. Our team isn’t changing. Our roadmap isn’t changing. And our mission – to empower creators to make their best work and get it in front of the audience they deserve – certainly isn’t changing.”

“Yahoo is the original Internet company, and Marissa and her team share our dream to make the Internet the ultimate creative canvas. I couldn’t be more excited to have her help. We also share a vision for Tumblr’s business that doesn’t compromise the community and product we love. Plus both our logos end with punctuation!”

Karp signs off not with a stodgy “Yours truly,” but with an exuberant use of the F-bomb-yeah combo that San Francisco Giants fans fondly remember pitcher Tim Lincecum saying on live TV after the team won the 2010 NL West title.